1. Field of the Invention
The invention relates to making of sheet metal ware and specifically to the manufacture of cylindrical metal container bodies. Method and apparatus for flanging container bodies, especially cans, is disclosed.
2. Description of the Prior Art
Substantially all metal can bodies used in the food and beverage industry are flanged at the end portion of the cylindrical can body in preparation for seaming an end closure panel to the can body. Common techniques for flanging container body ends include die flanging and roll flanging. Die flanging requires that the container body be forced over a single large flanging die that simultaneously flanges the entire circumference of the container edge. Roll flanging involves the application of one or more orbiting rollers to the edge of the container body, wherein the rollers are each in contact with only a small portion of the circumference, but by repeatedly rotating the orbiting rollers around the end circumference, it is possible to form a uniform flange on the entire circumference.
Metal can bodies are being constructed from increasingly thin material with the result that the edge adjacent to an open end of the can body is much more subject to cracking during the flanging process than was true when thicker materials were used. Roll flanging has been found to be a more desirable method of flanging than die flanging due to its apparently better ability to avoid cracking the flange during formation.
Among generally desirable goals remains the further elimination of flange cracking. It is also generally desirable to increase the speed at which flanging can be accomplished. However, increased speed often results in higher reject rates for cracked flanges. At fast speed for present flanging machines in the beverage can manufacturing industry is approximately one hundred cans per minute per roll flanging head.
A further generally desirable goal is to improve the reliability of flanging machines by reducing maintenance requirements. Excessive wear between sliding parts of prior flanging machines may be the cause of unnecessary repair expense and down time. It is therefore desired that all moving machine parts be bearing-supported both to reduce maintenance expense and to assure that the accuracy of the machine remains at a high level.
These and other goals are achieved as described below.